Halo: Combat Evolved, also known as Halo 1 or Halo: CE, is a First-person shooter science-fiction video game, created by Bungie Studios, which was a subsidiary of Microsoft Game Studios at that time. It was released for the original Xbox game console on November 15, 2001, and is backward compatible with the Xbox 360 by downloading a free code patch on Xbox Live. It was also released as Halo PC for PC and Mac in 2005. Additionally, it is one of the most popular video games of all time for the original Xbox with five million copies sold, a figure rivaled only by its sequel Halo 2, which achieved eight million sales.[1]

Halo: Combat Evolved has been made available as an Xbox Original game title for the Xbox 360 since December 4, 2007 for download on Xbox Live Marketplace for 1200 Microsoft Points. In June 2012, the game's price was lowered to 800 Microsoft Points.[2] A 10th year edition of the game was released for the Xbox 360 called Halo: Combat Evolved Anniversary on November 15, 2011, precisely 10 years after the original game, and the original Xbox, were released.

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Halo's storyline is linear. There is only one ending. It is presented to the player through an instruction manual, scripted events, in-game conversations, and a number of cut-scenes rendered using the game's graphics engine. This method of storyline delivery is common among modern video games. The Xbox version of Halo: Combat Evolved allows one player to play the campaign alone, as well as allow two players to play through the campaign in split screen. The PC version of Halo: Combat Evolved allows only one player to play through the campaign.

UNSC Pillar of Autumn emerges from Slipspace to find a huge ring — a "Halo" floating in space. The main character, Master Chief Petty OfficerJohn-117, is aboard the Pillar of Autumn when the ship comes under attack by the Covenant, an alliance of aliens and the mortal enemies of humanity. John-117 evacuates the doomed ship for the surface of Halo to protect the Autumn's artificial intelligence, Cortana. She carries highly sensitive military information, which would prove disastrous if she were captured by the Covenant. With the UNSC Marines by his side, Cortana providing direction, and his assault rifle ready and loaded, John-117 sets to finding out the mysteries of Halo and defeating the Covenant.

The first few levels of the game deal with an attempt to reach Halo's Control Room to uncover its purpose. It is soon discovered that during an attempt to take control of a research facility, both human and Covenant forces have accidentally released something: the Flood, as a result of the battle. The Flood is a parasitic race which received their name because of the way they swarm over all resistance. Free for the first time in thousands of years, the Flood sweeps across Halo, devastating Human and Covenant forces alike. The release of the Flood prompts 343 Guilty Spark, the eccentric Forerunner artificial intelligence, to activate Halo's defense systems. Most obvious among these are the Sentinels, flying robots equipped with beam projectors, but Halo's actual weapon is much more subtle and far more dangerous. Halo can fire a pulse that will wipe out all sentient life in a 25,000 light year radius. As sentient life is the Flood's food, the Flood will not be able to survive, and will therefore perish. Though the Installation only has a maximum effective radius of 25,000 light years, the pulse will trigger other installations as well. This system is designed to stop the Flood from spreading through the universe if they escape confinement from Halo, by starving the Flood of any life source large enough to sustain them. This is the only possible solution to the destructive parasite.

Naturally, this would wipe out Humanity as well as the Covenant, and so the final levels of the game revolve around John's attempt to destroy Halo before it fires.

The game leaves the story open to further developments, with the revelation that there are several Halo ring worlds in the galaxy, due to Halo being numbered Installation 04 by 343 Guilty Spark, the Monitor of the Installation. It is revealed later in Halo 2 that there were seven Halos before Installation 04's destruction.

The events which transpire in Halo's gameplay must be understood in the context of its backstory, created by Bungie and elaborated in several novels written after the release of the game. Noteworthy is its use of the oft-used battle between monoculture radicalism and free culturalism. Also present, although less pronounced, is the likewise popular theme of blind religion (Covenant) versus free-thought secularism (UNSC). A summary of this back story is presented below.

2160-2200: This is a period of brutal unrest in Human history in which National governments and break-off factions fight for control of Earth and its colonies.

As overpopulation and unrest mounted on Earth, a number of new political movements were formed including the neo-communist Koslovics, led by Vladimir Koslov, and the neo-fascist Frieden based on the Jovian Moons, which attacked the UN Colonial Advisers on one of the moons. UN-sponsored military forces began a pattern of massive build-ups which culminated in the Jovian Moons campaign, the Rain Forest Wars and the first Interplanetary War. After the successful Marine attack on Mars, recruitment drives and propaganda tactics strongly bolstered UNSC forces. They defeated the Koslovics and the Frieden on Earth and crushed their remnants throughout the Solar System. Both factions were defeated in the face of massive, unified UN military.

In the year 2291, the UNSC successfully developed humanity's first Slipspace drive, the Shaw-Fujikawa Translight Engine. For the first time in history, the rapid colonization of other worlds was made possible. By 2390, 210 worlds had been occupied by humans, and were being actively terraformed to suit man's needs. These worlds were to become known as the Inner colonies. By 2490, the UNSC's fledgling interstellar empire had expanded to over 800 planets throughout the Orion Arm of the Milky Way galaxy. During this period, the planet Reach became the headquarters of the UNSC military, and was destined to become the most heavily fortified world under human control.

In 2517, several years before contact with the Covenant, the UNSC military embarked on a secret project to create a group of super soldiers that would deal with occasional unrest in the Colonies. Codenamed SPARTANs, these genetically enhanced troops were trained from the age of 6 into a life of battle, and became a great asset against the Covenant. While humans suffered defeat after defeat in space, they could almost always prevail with the help of the SPARTANs in ground engagements. The main character of Halo's gameplay, John-117, is a veteran SPARTAN of the SPARTAN-II project after an unfortunate failure of the first SPARTAN program (code name Orion). All SPARTAN-IIs were given special armor designated Mjolnir, which can increase their strength and speed. They were the only ones who could wear it as those without physical augmentation would not be able to withstand the reaction times of the armor and die.

After first contact with the Covenant was made on the colony of Harvest in 2525, a series of brutal engagements followed. AdmiralPreston Cole's fleet managed a victory at Harvest, but at a high cost - two thirds of his ships were destroyed. Despite significant tactical brilliance on the part of Human commanders, Covenant technology guaranteed a four to one kill/loss ratio in most space battles. One by one, the Outer Colonies fell below the onslaught, and by 2535, virtually all had been destroyed.

By 2552, the Covenant had destroyed many of Humanity's Inner colonies. In a move of desperation, UNSC orders a secret plan to capture a Covenant ship using a SPARTAN task force and find the coordinates of their home planet. All of the Spartans except three are chosen for this mission, and, led by John-117, board a specially outfitted ship known as the Pillar of Autumn (under the command of Captain Jacob Keyes). This plan, however, is interrupted when the Covenant launch a surprise attack on the fortress world of Reach.

During this battle, Reach is overrun and the human fleet is obliterated. Worse still, John-117 thinks that all of the SPARTANs but himself are killed on the surface of the planet. The (supposedly) last remaining Spartan, John-117, escapes with the Pillar of Autumn. In accordance with the Cole Protocol, the Autumn makes a blind Slipspace jump, and emerges in the vicinity of an unexplored and remarkable world.

The Pillar of Autumn exits Slipspace to find a mysterious ring shaped space station orbiting a gas giant. The ring, quickly named "Halo," is obviously artificial. A Covenant fleet, however, is also present, and a subsequent battle heavily damages the Autumn. Captain Keyes initiates the Cole protocol 2 - all records of Earth's location are erased, the shipboard AI Cortana is given to John-117 to protect from the Covenant, and the Autumn is crash landed onto Halo. Cortana leaves the Autumn with John-117 in a Bumblebee escape pod which also crash lands on Halo.

Game play begins in earnest with John-117's escape from the Autumn, and continues upon landing. The player will soon discover the origins and purpose of this world - and uncover a threat that forces even the Covenant into retreat.

Halo's gameplay was characterized by several features which set it apart from less acclaimed first-person shooter games of its time.

Storyline Execution:Halo's gameplay and storyline are tightly interwoven, delivering in a convincing manner being consistent with the flow of the game.

Vehicular Incorporation:Halo includes the option for players to control multiple land and air based vehicles in third-person view. This Third-Person vantage brings a welcomed sense of immersion and enhances the specific points of gameplay, again setting Halo apart from contemporary first person shooters.

Weapons System:Halo's new weapons system is unique in two major respects. The first is allowing players to carry only two weapons at a time, thus forcing the player to make trade-offs as they progress throughout the game. The second change is a separate button for throwing Grenades.

Artificial Intelligence:Halo's AI is quite sophisticated for its era. With a brand new advanced AI system, actions performed by the AI such as panicking after the death of a superior, diving out of the way of an oncoming vehicle, or taking cover from explosives and suppressive fire, helped Halo stand out from the rest of the first-person shooters being released at the time.

Movement in Halo is similar to other first-person shooters, allowing the player to move forwards, backwards, and strafe left and right independently of their aim. On the Xbox, moving and aiming are normally separated between the two analogue sticks; and on the PC, between the mouse and the keyboard. Halo also allows the player to crouch and jump, although jumping from a high ledge will often result in death, or at least major fall damage. Damage from falling can be reduced or negated entirely with a well-timed crouch right as one lands. Additionally, if the player crouches at the peak of his jump he will be able to land on something slightly taller than if he were to jump without crouching. Also, if the player is jumping from a cliff he can make sure he is touching the wall periodically while he is falling. This will count as if he is touching floor, and every time the player touches the wall, the damage counter goes to zero. However, there is no visible damage counter during gameplay.

The A.I. in Halo was superior to many other games at the time because the A.I. was sophisticated enough to attack other enemies in the vicinity, not just John-117. If there is another faction in the area, the A.I. will engage it in the same way as they would fight John-117.

Three factions of enemies are encountered on Halo:

The Covenant: The Covenant, whose Fleet of Particular Justice was led by the Supreme Commander, Thel 'Vadamee, is an alliance of different species. This includes the cowardly Unggoy, the Kig-Yar with their portable Energy Shields, the Sangheili, master tacticians with their body-covering Energy Shields, and the huge, metal Hunters with remarkably strong armor composed of some unknown alloy. The Covenant troops mostly carry plasma weapons of various power. They also make extensive use of vehicles such as Ghosts, Wraiths, Shades, and Banshees.

The Flood: The parasitic Flood are encountered in three forms. The Infection Forms themselves, which usually die from a single shot or John-117's energy shield. Exploding Carrier Forms, which cause major splash damage and release Infection Forms. Not forgetting the Combat Forms of former Humans or Sangheili whose nervous systems have been taken over by the parasite. Combat forms are the main and toughest of the three types. They often carry a Human or Covenant weapon.

Sentinels: These ancient robotic constructs are controlled by the Forerunner AI Monitor of Installation 04, 343 Guilty Spark. He is tasked with the defense of the ring against possible threats and to control the Flood infestations. Sentinels fire an orange colored beam that can strip hostiles of their Energy Shields. This weapon is designed to burn the Flood and has proven effective against many other enemies.

UNSC Marines: The Pillar of Autumn's complement of Marines assists the player often in the game. They are helpful, but on higher difficulties they are easily killed by enemies. They wield a variety of weapons. These include the Assault Rifle, Sniper Rifle, Shotgun, Needler, and Plasma Rifle. Marines armed with Assault Rifles will occasionally throw Fragmentation Grenades. The Marines will willingly ride in Scorpions and Warthogs with the player and use the Chaingun on the Warthog while the player is driving. Unfortunately they are incapable of actually driving either vehicle. The only vehicle that Marines can drive is the Ghost, which they pilot only briefly. They appear in every level until the Library. When Marines are near death they will go into a berserk state, attacking every visible enemy.

UNSC Crewmen: The crewmen of the Pillar of Autumn appear briefly as allies in the game. They are armed with Pistols, but occasionally appear in combat unarmed. They have lower health than Marines and are prone to retreating and cowering in battle. They only appear in the levels Pillar of Autumn and Halo. One melee is often enough to kill them and their habit of cowering tend to make them an obstacle to their comrades.

Sentinels: Part of Halo's defense system, the Forerunner Sentinels, led by the Monitor 343 Guilty Spark, are hovering robotic drones. They attack the Flood, Covenant, and eventually John-117. Although possessing a powerful Beam Weapon, they are not particularly resistant to damage (Their shields are especially vulnerable to Covenant weaponry, especially overcharged Plasma Pistols and explosives). They are seen as Normal and Shielded variants although both can be destroyed relatively easily. They help the player in the levels 343 Guilty Spark and The Library, but are enemies from the level Two Betrayals until the end of the game, acting as a Fourth Faction that attacks the Flood, Covenant, and the player when encountered.

All usable weapons in Halo: Combat Evolved belong to either the Covenant or the UNSC. The player can carry two weapons and up to 8 grenades (Four Fragmentation Grenades and Four Plasma Grenades).

Covenant weapons are better suited for reducing shields and typically fire slower than human weapons. With the exception of the Needler, they do not require ammunition or reloading. Instead, each weapon comes with its own battery. Once the battery is depleted the weapon must be discarded. Covenant weapons can also overheat (except the Needler) if fired for too long, after which they must be given time to cool down before they can be used again. There are a total of five Covenant weapons in the Campaign, three of which are usable by the player: the Plasma Pistol, Plasma Rifle, and the Needler. The two weapons the player can't use are the Energy Sword, which destabilizes after you kill the Sangheili using it, and the Fuel Rod Gun, which explodes after you kill the enemy using it. There are two additional weapons in the multiplayer mode of the PC version only, the Fuel Rod Gun and Flamethrower. A plasma based weapon of the same type but with greater charge than the player's current one will appear as a swappable weapon. If the weapon has lesser charge, it is not swappable until the player's current charge falls low enough. Needlers automatically collect any ammunition from other needlers the player moves over. Needlers can also use some very rare individual packs of projectiles.

Human weapons, on the other hand, require ammunition and constant reloading. They are better suited for reducing health and do not overheat. However, on the Easy and Normal difficulty settings the difference is often negligible. There are five human weapons (not counting Fragmentation Grenades) usable in the Campaign and six in the Multiplayer of the Halo PC.

Pistol - The M6D is a powerful, accurate weapon that can be used up to 124 meters. It has good magazine capacity (12 rounds), a 2X zoom scope for semi-sniping, and its bullets create a very small explosion on impact. The M6D Pistol is semi-automatic and recoil operated. If used correctly it can be the best back up weapon in the game, especially when you are sniping and don't have a Sniper Rifle. It can kill another player with three shots to the head and can dispatch a Hunter with one shot to the back if you accurately hit their exposed flesh. It has been said to be one of the most effective weapons in the game, as it is fast, accurate, and deadly in the hands of a professional. In fact, the only level it does not appear in, "Truth and Reconciliation," is made difficult without this weapon, so the Sniper Rifle with more ammo capacity is used instead.

Assault Rifle - The MA5B Assault Rifle is an automatic gas operated rifle that fires 7.62x51mm armor-piercing rounds. It has low damage per hit, and low accuracy at medium to long ranges. This weapon is good for close and medium ranges. The player will start off with one in most levels. It is a decent all around weapon, with a fast melee and good maneuverability. It is one of the best weapons against infection forms, Unggoy, invisible Sangheili, and sometimes Hunters. An interesting note is that no matter what weapons you're wielding, all of the cutscenes in Halo: Combat Evolved have John-117 holding an Assault Rifle - even in Two Betrayals, where your starting weapons are the M90 Shotgun and the Plasma Pistol.

Shotgun - the M90 Shotgun is practically the best weapon for picking off Flood Combat Forms and Carrier Forms, killing them with one hit if you are close enough. It is highly effective against Sangheili also. The shotgun fires a burst of 15 pellets, causing enemies in close range to be completely decimated in less than a second. Medium range is not so effective, and long range is useless altogether. Its close range capabilities are unmatched and are what makes it so effective against the Flood.

Sniper Rifle - The S2 variant of the Sniper Rifle features a night vision enhancement to the scope, which plays an essential part at the start of Truth and Reconciliation. Its devastating power and range make it a formidable part of your arsenal. It carries four bullets per magazine and can pick off most enemies instantly, depending on their rank and the difficulty the player is playing. The Flood are barely affected by this weapon, sometimes taking 12 sniper shots to kill one. Thus, it is not worth the ammunition, which is often hard to come by on levels featuring the Flood.

Rocket Launcher - The Rocket Launcher is a devastating piece of equipment when used correctly. The Rocket Launcher will kill anything with one direct hit except Hunters and higher-ranking Sangheili on Legendary difficulty. It is the player's best choice against vehicles and groups of infantry.

Fragmentation Grenade - The technically named M9 HE-DP grenade, more commonly known as a Frag Grenade, will easily kill anything without a shield. Its bounciness gives it the edge in distance over the Plasma Grenade and it also packs a lot of force and splash damage. This means it is useful for Grenade Jumps.

Warthog LAAG - The LRV Light Anti Aircraft Turret is always equipped on the back of a Warthog, serving its purpose of eliminating enemies and vehicles quickly and effectively. Prolonged fire degrades accuracy.

Flamethrower - Usable only in multiplayer in Halo PC. It launches a stream of burning fuel over a relatively short distance, causing damage to enemies in front of the weapon and hurting them after they have been hit. It also has a very limited ability to set a surface on fire for a very short period of time. It fires from a unit mounted fuel tank that counts down from 100 to 0 units of fuel.

Energy Sword - A deadly weapon used by Zealot Sangheili and Field Master Sangheili. It can kill the player in one hit (although not on Easy difficulty where it takes three). It is advisable to dispatch the wielder quickly. The player cannot use the Energy Sword due to a built in fail safe.

Plasma Rifle - It is a common light weapon in the Covenant army, only wielded by Sangheili. The Plasma Rifle has a high rate of fire and deals out a moderate amount of damage. A Plasma Rifle with a shotgun makes a good combo, Plasma Rifle for medium range and shotgun for close range. On Legendary, the Plasma Rifle is the most effective mid to close range weapon, best paired with an M90 Shotgun. It is also very useful for depleting Sangheili shields.

Plasma Pistol - The Plasma Pistol, like the Plasma Rifle, is a directed energy weapon that fires bolts of superheated ionized gas otherwise known as plasma. Continuous application of the firing mechanism will allow a buildup of plasma, called overcharging that, when fired, will instantly and completely deplete shields regardless of strength. This overcharging makes it a valuable weapon in Multiplayer and against Sangheili, Kig-Yar, and Sentinels in Campaign, usually when paired with an M6D Pistol. An overcharged Plasma Pistol also has a limited tracking ability, which can be useful to take down fast moving Sentinels and unsuspecting Sangheili.

Needler - The Needler fires semi-homing crystal shards that explode approximately ten seconds after being launched and ignore most forms of personal energy shielding. While one explosion produces fairly light damage, several crystals exploding in succession can multiply the damage to fatal levels, and even more crystals in the same enemy will produce a large explosion. It is strange that independent ammunition that isn't already in another Needler is only available in 343 Guilty Spark .

Fuel Rod Gun - The Fuel Rod Gun is used by the strongest and weakest of the Covenant species. It is carried on the shoulders of many Special Operations Unggoy, and a modified version is directly attached on the right arm of Hunters. In Campaign mode the gun explodes when its Covenant wielder is killed. It is wieldable in the PC version on most multiplayer maps. It has a limited battery when used by a player.

Plasma Grenade - The Covenant Plasma Grenade is one of the most ingenious weapons in the game. Once activated, its outer layer converts to plasma, enabling it to fuse/stick to whatever it impacts (except for most walls and Hunter armor). It generates an electro-magnetic pulse that drains instantly any kind of shielding, no matter how strong it is, making it deadly even to enemies who survive the initial explosion. It is also handy for sticking enemies themselves, especially Unggoy, who tend to run toward their comrades when panicking, as well as Sangheili Zealots.

Shade - A stationary gun turret manned in third-person like a vehicle. It consists of a stand and a floating 360 degree rotating turret-like seat with control systems to its gun. It has a strong anti-tank ability, but the Covenant use it mainly against infantry. It can be manned by Sangheili, Unggoy and the player and is similar to the turret mounted on Spirit-class drop ships.

Warthog LAAV - A UNSC Light Anti-Armor Vehicle. The M12A1 is another variant of the Warthog with a triple barreled 102mm Rocket Launcher. It only shoots three rockets before reloading. Available only in Multiplayer on the PC version of Halo: Combat Evolved.

Scorpion - A UNSC Main Battle Tank. It has a powerful 90 mm cannon mounted on a turret, affixed to the rear of the chassis. It also features a 7.62mm machine gun aside the main cannon. It should be noted that both the main cannon and machine gun are inaccurate at medium to long range distances.

Ghost - A Covenant Reconnaissance and Rapid Attack Vehicle. Its twin Plasma Cannons complement its high speed and agility, Allowing the user to blast enemies with the guns and run them into the ground. It is destructible in Campaign. It also has a feature that increases anti-gravity power in the front, causing the Ghost to nose up. This can be used to stabilize the Ghost after gliding over a cliff or hill, or to splatter opposition. Unlike Halo 2 and 3, this model has no boost but fires faster than its later models.

Banshee - A Covenant Aerial Assault Aircraft. Very maneuverable. Armed with two plasma cannons and a fuel rod cannon. The Banshee's armor is strongest in front and very weak on the sides and back. It is destructible in Campaign but is, like all vehicles, impervious to permanent destruction in Halo PC's multiplayer. Unlike Halo 2 and 3, this model has no boost, and fires slower, making it an earlier, less effective model. The Banshee is unavailable in Multiplayer in the Xbox version. It is probably the lightest vehicle as it can take less than a M6D magazine before it blows.

Several vehicles are not controllable by the player, like the UNSC Pelican Dropship, the Covenant Spirit dropship, and the Covenant Wraith Mortar Tank. The Wraith requires ballistic aiming, firing large Plasma Bombs in arcs towards its enemies, similar to artillery. These bombs, if they score a direct hit, will often destroy vehicles or kill a Spartan if he/she is not equipped with an Overshield. Wraiths can be destroyed with explosive weapons such as the Scorpion's Main Cannon and the Rocket Launcher.

Also, it is very easy to splatter enemies in Halo: Combat Evolved because the game's physics engine cannot discern between a fast and slow-moving vehicle, thus making it so that a slight touch, even by accident, will kill it. This is especially frustrating on the level "The Silent Cartographer"'s LZ, as Marines tend to dive underneath the level's many Warthogs, and in multiplayer, since the player can easily be killed by unoccupied vehicles.

Halo features a wide variety of environments including human and Covenant star ships, ancient buildings on Halo itself, and expansive outdoor climates. The first level, Pillar of Autumn, is fought entirely on the human star ship of the same name. The next level, Halo, takes place in a temperate highland climate with open-air Forerunner structures scattered about. This level also contains the famous "Blue Beam Towers." Truth and Reconciliation begins in a rocky desert, but the setting changes to the titular Covenant cruiser about one-third of the way through. The Silent Cartographer occurs on a tropical island, with substantial combat both outdoors and inside futuristic Forerunner installations. Assault on the Control Room takes place in a snowy, icy area of towering cliffs and underground tunnels as well as high-tech suspension bridges and oft-repeated Forerunner structures built into and through cliff walls.

343 Guilty Spark is a significant departure from these majestic environments, with combat in gloomy, exotic swamps and equally gloomy underground complexes that host the player's introduction to the Flood. The player is then teleported to the second of three entirely indoor levels, The Library, encountering repetitive, foreboding hallways and massive elevators. John-117 returns to the snowy climate of Assault on the Control Room for Two Betrayals, visiting almost no new areas but, interestingly, traveling in the opposite direction. Keyes occurs in the same rocky deserts and the same Covenant ship from Truth and Reconciliation, albeit now heavily damaged, but this time the Flood are present in huge numbers. Finally, The Maw is set on the Pillar of Autumn with three major differences: the presence of the Flood, the heavy structural damage, and access to the Engineering section and service corridors of the ship, which were previously off-limits. In total, six of the ten levels feature a substantial amount of combat outdoors.

Up to four players can play together using the same-console split screen mode. It is also possible for up to 16 players to play together in one Halo game over a local area network, using Xbox and/or Xbox 360 consoles that have been connected through an Ethernet hub, or via Xbox Connect, which is a way of tunneling a connection via a PC. The game's seamless support for this type of play, and a few large maps that can accommodate up to 16 combatants, is a first for console games. Since the game was released before the launch of Xbox Live, mainstream online play was not available for this title. The PC version of Halo: Combat Evolved officially adds online play, also new vehicles (Banshee and Rocket Warthog), weapons (Fuel Rod Gun and Flamethrower) and maps (see list below) for multiplayer. The PC version of Halo: Combat Evolved does not support split screen multiplayer.

Health: The player in Halo has limited, non-regenerating health, which can be fully restored by picking up health-packs. This aspect of the game was changed in Halo 2, but returned in Halo 3: ODST and Halo: Reach. Running completely out of health will result in death, but having lower health does not impede player actions. A player's health can be reduced only if his shields have been depleted. If the player's health is at minimal levels they will faintly hear John-117's heartbeat. When the non-regenerative health idea was abandoned in Halo 2 the medic packs disappeared completely.

Shields: John-117's Mjolnir Mk. V armor has a built-in shield, which protects all parts of his body from damage. The shield will decrease in strength every time it is hit by a weapon and will fail after taking too many hits. The amount of shield drain depends on the attacker's weapon but will quickly regenerate if it is not hit for a brief period of time. The shield represents a marked departure from most first-person shooters, in which one's health bar is basically augmented by picking up "armor." It is possible, in the single-player campaign at least, to have insufficient health points to survive the next section of game-play. Halo players, on the other hand, have a more-or-less permanent buffer of health at their disposal (assuming they manage to find time to regenerate the shield), making it less of a disaster to take hits in combat.

Active camouflage: Drastically reduces the player's visibility for approximately 45 seconds, making all but a faint outline of him transparent. This effect is reduced or void if the player is holding a flag or skull (in multiplayer), hit by weapons fire, fires their weapon, or when time runs out.

Overshield: An enhanced, non-regenerating shield which is two times, (three times on enemies) the strength of the normal one. The overshield functions on top of the regular shield; when it is active, the normal shield does not take damage. In the single player game, the overshield is reduced only when the player is hit, while in the multiplayer game, it weakens gradually over time. One fully charged Plasma Pistol shot can take out the overshield and regular shield entirely. Additionally, while the over shield is charging, the player is completely invincible against almost every type of damage. The player can still be killed by assassination, however.

Due to its huge retail success, Halo: CE received a Xbox Classics edition. This version is essentially identical to the standard edition, except with a commemorative box art. It was available for a reduced price,[citation needed] but has now stopped production.

Again, due to its record-breaking sale numbers, a Platinum Hits edition of Halo: CE was produced. This version, like the Classics Version, contains the same content as the standard edition, but with a different box art. This version is no longer in production.

In 2000 at E3, Bungie showed off a trailer of the upcoming game to the public. This trailer featured Marines along with John-117 scouting out a Forerunner structure and the Covenant fighting them. During this trailer there was still no active AI so all the Covenant was actually controlled by Bungie. This trailer was before the conversion to the Xbox as an FPS.

The Cortana Letters are a series of cryptic emails from "cortana@bungie.com," sent to a very prominent Marathonsite before the release of the game. At the time, it was not known who Cortana was, and her emails offered a small glimpse of the Halo Trilogy plot. The letters were supposedly authored by the former Bungie employee Nathan Bitner.It should be noted that the Cortana Letters were sent while the game was still in production, and Cortana is greatly out of character. As such, these letters may currently offer little insight into the plot. Although Cortana does reference the first letter in Halo 3, Bungie has said the material of the letters is only to be considered canon when used in current Halo material.

Halo was the main launch title for Xbox and is said to be the game that made the Xbox what it is today. It is widely renowned for saving the fledgling Xbox platform, as the Xbox lacked any titles to compete with Sony's PlayStation 2 or Nintendo's GameCube. Halo became an overnight success and managed to drive the platform from the brink of an early death. It went on to sell 8 million copies, in other words, 33% of all Xbox owners also owned Halo. It was also critically acclaimed. IGN gave the game a 9.7 out of 10 and stated it to be the best Xbox game of all time. X-Play gave it a perfect 5 out of 5. The game got a perfect ten from EGM, and was 2002 Game of the Year for IGN, EGM, OXM, and AIAS. It also got a 9.5 out of 10 from Game Informer, and an average meta-score of 97 out of 100, making it the most highly rated Xbox game of all time. It was also called the game that reinvented a genre. OXM rated Halo: CE Number 1 in a list of the 100 best games of recent memory, saying "The Xbox did not create Halo, Halo made the Xbox."

Halo Original Soundtrack, composed and produced by Martin O'Donnell and Michael Salvatori for the video game Halo: Combat Evolved, is one CD comprising 26 tracks. Some editions include a bonus DVD with game trailers for Halo 2. Most of the music from Halo: Combat Evolved is present on the CD, although some songs are remixed and some tracks are intermixed with others in medley form. It was released in 2001.

Halo was originally being developed for the Mac and PC as a real time strategy game (similar to Halo Wars), before Microsoft took interest in its development and purchased Bungie Studios, thereby owning a promising video game to use exclusively with the Xbox.

There are 8,087 lines of dialogue in the game, most of them randomly triggered during combat.[3]

The Halo: Combat Evolved box art shows the Banshees in the background in their pilotless stance, yet they are still flying. Similarly, they are shown firing thin laser beams, rather than the plasma orbs that they actually fire in-game.

Bungie mentioned that none of the characters in the E3 video for Halo: Combat Evolved had AI. In fact, all of the movement was actually scripted. This, however, was proven to be partly false. The AI will move to what are called "firing positions," which are not only places that the AI fire from, but places which the AI will not stop moving unless already in one, save for scripted command lists, although the AI will usually attempt to move to a firing position.

Halo: Combat Evolved was originally going to have most of the weapons that were introduced in Halo 2 and Halo 3, but due to time constraints, most of the weapons were cut from the final version.[4]

In the Halo: Combat Evolved handbook, the Plasma Rifle's "blueprint" is an overlap of a Needler underneath and the rifle on top.

Halo: Combat Evolved was originally planned to have a changing weather system, which was mentioned in the August 2000 issue of PC Gamer magazine.[5]

Halo: Combat Evolved was not the original title made by Bungie; the original title of the game had always been intended to be simply "Halo." The subtitle "Combat Evolved" was added by Microsoft Game Studios during Halo's development phase, believing "Halo" by itself was not a descriptive enough title (much to Bungie's irritation). This can be proved that in the main menu the title is labeled simply as "Halo." The title is also labeled simply as Halo on the side of the box. Also, the game's official soundtrack lists the game as simply Halo.[6]

Halo: Combat Evolved was a launch title for the Xbox, as well as the only Halo title to be a launch title for any Xbox system so far.

This is the only game in the series with only a single named antagonist: 343 Guilty Spark.

Though there are no special editions of the game, there is a rare version of it. Most copies of the game feature the words "Game of the Year" on a golden star with reviews on the back. An original copy of the game features none of these on it. Copies of this version are extremely rare but are usually cheap. The Game of the Year edition features a slight change to the cover's artwork. The original doesn't show John-117s index finger on the Assault rifle while the Game of the Year edition does. Also the Banshee closest to the left has been moved closer to the right so the Game of the Year star doesn't cover it up.

It has been stated by Bungie that Halo: Reach was inspired from Halo: Combat Evolved.

Originally, the game's campaign was to have a lot more action and many Marines surviving. In some of the trailers, there are scenes where the Covenant and the Marines face to face against each other in more numbers and there are 3 Pelicans assaulting Covenant positions in Assault on the Control Room as seen on the TV Spot of Halo: Combat Evolved.

In celebration of Halo's 10th anniversary, 343 Industries remade Halo: Combat Evolved. It's appropriately named Halo: Combat Evolved Anniversary. This game hit store shelves November 15, 2011, which is exactly 10 years after the first Halo's release, and the release of the original Xbox.

Halo: Combat Evolved is available to buy in the Xbox 360's Xbox Live Marketplace for 800 Microsoft Points.

Halo: Combat Evolved is the only Halo game to feature Overshield and Active Camo pickups during the campaign. Overshields are represented as translucent clear cubes containing maroon spheres, while Active Camo is represented as a clear pyramid containing a light blue sphere. Overshields in this game do not deteriorate over time and can only be taken down by taking damage. Active Camo also has the same effectiveness if you are moving or not.

Halo: Combat Evolved was originally going to feature the Hummer instead of the Warthog.